NCC 2022 Ventilation Requirements
How room ventilation, H6V3 airtightness verification and condensation management fit together in South Australia.
Current in South Australia: NCC 2022 Amendment 2 remains the applicable Building Code until 30 April 2027. South Australia will adopt the Building Code provisions of NCC 2025 on 1 May 2027. This guide explains room ventilation under Part 10.6, H6V3 building-envelope sealing, and the exhaust and condensation-management provisions in Part 10.8.
Looking for the full South Australian picture, including airtightness, the SA commencement dates and compliance pathways? See our pillar guide: NCC 2022 & NCC 2025 in South Australia.
Why NCC 2022 changed ventilation requirements
Australian homes have become progressively more airtight over the past two decades. Better insulation, more careful construction practice, improved window sealing and draught-proofing have all reduced uncontrolled air leakage. This is good for energy efficiency and thermal comfort — but it creates a problem for indoor air quality.
In a leaky home, a certain volume of fresh air enters through gaps and cracks even when all windows are closed. This uncontrolled infiltration — while thermally inefficient — incidentally dilutes indoor moisture, CO₂ and pollutants. As homes have become tighter, this incidental dilution has reduced, and indoor air quality problems have increased.
NCC 2022 recognises this relationship within H6V3, an optional Verification Method for building-envelope sealing. Where that pathway is used and the air-permeability threshold is met, designed mechanical ventilation is required. That is different from a universal ACH50 trigger applying to every home.
The key changes
Building-envelope sealing verification
Verification MethodWhat it requires
Where H6V3 is used and verified air permeability is not more than 5 m³/(h·m²) at 50 Pa, a mechanical ventilation system must be provided in accordance with the Verification Method.
The formula
For continuous operation: Q (L/s) = 0.05 × Floor Area (m²) + 3.5 × (Number of Bedrooms + 1). The full formula includes a time fraction for intermittent operation.
What this means in practice
A tighter building needs designed ventilation, but H6V3 does not prescribe MVHR and its air-permeability unit is not interchangeable with ACH50. The selected ventilation solution must suit the nominated pathway and the building.
Example calculation
For continuous operation in a 220 m² four-bedroom home: 0.05 × 220 + 3.5 × 5 = 28.5 L/s. Final system sizing must also account for layout, pressure losses, controls, balancing and the project's complete requirements.
Exhaust systems — condensation management
Exhaust / CondensationDirect outdoor discharge required
Exhaust fans in kitchens, bathrooms, sanitary compartments and laundries must discharge directly to outdoor air via a duct or shaft. Venting into a roof cavity, sub-floor or wall cavity is explicitly non-compliant. This rule closes one of the most widespread and damaging installation errors in Australian residential construction.
Light switch interlock with 10-minute run-on
For bathrooms and sanitary compartments that do not have natural ventilation (i.e. no operable window or opening to outside), the exhaust fan must be wired to the light switch. It must turn on when the light is switched on, and continue running for a minimum of 10 minutes after the light is turned off. This ensures adequate post-shower extraction.
Why this matters
Inadequate bathroom exhaust is the single most common source of moisture damage in residential buildings. Ducting into a roof cavity — even with the best intentions — creates a long-term condensation and mould problem that is expensive to remediate and is typically not covered by building warranty.
External walls — vapour permeance
CondensationClimate zone-specific requirements
NCC 2022 introduced requirements for wall sarking vapour permeance classified by climate zone. Membranes in Climate Zones 4 and 5 must be Class 3 minimum vapour permeance. South Australia spans several NCC climate zones — see our full SA climate zone and compliance breakdown for exactly which zone applies to your site.
Purpose
Moisture drive through wall assemblies varies significantly by climate. In temperate and cool climates, moisture can condense within the wall cavity — on the inside face of sarking or within insulation. Appropriate vapour control management reduces this risk, particularly in airtight, well-insulated homes where wall cavity temperatures may differ significantly from indoor conditions.
Which climate zone is your site in? Vapour permeance and roof ventilation requirements vary across South Australia — Adelaide, the Hills, the South East and the north all sit in different NCC climate zones. See our full SA climate zone breakdown for the region-by-region detail.
Do not confuse air permeability with ACH50
H6V3 uses air permeability in m³/(h·m²) at 50 Pa. ACH50 measures air changes per hour relative to the building volume. Both can come from blower door testing, but they are different results and cannot be substituted for one another. See what is ACH50 for the full explanation. These ACH50 figures are useful performance benchmarks, not universal NCC pass-or-fail thresholds:
The right target depends on the project brief and certification pathway. Set it deliberately, coordinate ventilation around it and verify the result where the project relies on measured performance.
Does NCC 2022 require blower door testing?
Not universally. A measured test is required when a project uses H6V3, claims an airtightness input in a NatHERS assessment, targets Passive House certification or otherwise relies on a tested result. Testing can also be specified as a voluntary quality-control measure.
Many builders and designers in South Australia are already specifying blower door tests proactively — to confirm compliance, de-risk defects claims, and demonstrate performance to clients. HiPer Haus provides blower door testing services across Adelaide and South Australia with full written reporting. See preparing for a blower door test and can you fail a blower door test for what to expect.
How MVHR can fit the project pathway
A properly designed and commissioned MVHR system can provide controlled outdoor air and continuous extract, but it does not automatically establish whole-project NCC compliance:
H6V3 — minimum airflow
Where H6V3 applies, the system must meet its calculated airflow, controls and operation requirements.
Kitchen extraction
General MVHR kitchen extract does not replace a compliant rangehood strategy. Discharge and make-up air require separate coordination.
Part 10.8.2 — continuous extraction
MVHR runs 24 hours a day at a set flow rate, ensuring bathrooms are continuously in negative pressure relative to living spaces — far exceeding the intermittent extraction of a standalone fan.
CO₂ and IAQ
Supply terminals in bedrooms and living areas deliver continuous fresh, filtered outdoor air — preventing the CO₂ accumulation that the code does not yet explicitly address but that affects occupant health and sleep.
Frequently asked questions
What did NCC 2022 change for ventilation in homes?
NCC 2022 separates room ventilation, building-envelope sealing and condensation management. Part 10.6 sets out ventilation provisions for rooms. H6V3 is an optional building-envelope sealing Verification Method that requires mechanical ventilation where verified air permeability is not more than 5 m³/(h·m²) at 50 Pa. Part 10.8 includes requirements for exhaust discharge, wet-area fan controls and wall or roof moisture management.
What is the NCC 2022 mechanical ventilation formula?
The minimum required airflow for a dwelling is calculated as: Airflow (L/s) = 0.05 × Floor Area (m²) + 3.5 × (Number of Bedrooms + 1). For example, a 200 m² four-bedroom home requires a minimum of 0.05 × 200 + 3.5 × 5 = 10 + 17.5 = 27.5 L/s of mechanical ventilation.
Does NCC 2022 require airtightness testing?
NCC 2022 does not mandate airtightness testing for all homes. Testing is required where a project relies on a measured result under its nominated pathway, including H6V3, a NatHERS airtightness credit or Passive House certification. Other projects may test voluntarily to verify performance and find leakage defects.
Does MVHR satisfy NCC 2022 ventilation requirements?
Not automatically. A properly designed and commissioned MVHR system can form part of a compliant ventilation solution, but the result depends on the nominated NCC pathway, airflow, controls, discharge and other project-specific requirements. General MVHR kitchen extract does not replace a compliant rangehood strategy.
When did NCC 2022 come into effect in South Australia?
South Australia adopted most of NCC 2022 on 1 May 2023, but deferred the 'modern homes' provisions — the 7-star energy efficiency target, livable housing design and the improved condensation management measures — to 1 October 2024. For new Class 1 and Class 2 homes, the condensation management requirements (and the energy provisions that drive airtightness) apply to development applications lodged from 1 October 2024. Alterations and additions to existing homes have a further concession until 1 May 2030.
Working on a project in South Australia?
HiPer Haus provides MVHR design, installation and commissioning for new homes and renovations across Adelaide and SA, plus blower door testing for project verification and Passive House certification.
Written by
Jonathen HindryFounder of HiPer Haus. ATTMA Level 1 Airtightness Tester, Certified Passive House Tradesperson and 25+ year plumber — blower door testing, MVHR design and heat pump hot water across Adelaide and South Australia.
